263 
THE GEOLOGIST. 
the latter case, tlicrc will be more or less separation of the solid and coarser from 
'the finer and liquid particles, into different zones or layers ; those composed of 
tho former moving loss readily than those composed of the latter ; and also that 
the former will, by the friction attending this process, he turned round so as to 
bring their major axes into the line of direction of the movements; and, if 
susceptible of tension or disintegration, will be elongated or drawn out in the 
same direction. 
Ill illustration of this law, specimens of marbled paper were produced, being 
Impressions from superficial films of coloured matter rtoatiiig upon water in cir- 
cular or irregular forms, after they had been subjected to motion in one or more 
directions by lateral pressure; the appearances produced bearing a very exact 
resemblance to those presented by the lamination and occasionally sinuous or con- 
torted structure of the ribboned lavas of Ponza, Iseliia, the Ascension Isles, &c., 
as well as that of gneiss and mica-schist. 
The author proceeded to state that the expansion of a subterranean mass of 
granite by increase of temperature, to which all geologists agree in ascribing 
the elevation of overlying rocks, miisf be accompanied by great internal movements 
and consequent mutual friction among the component parts, and even among the 
individual crystals ; that if a lubricating ingredient, such as water holding silex 
ill solution, or gelatinous silex, be intimately mixed up \\-ith the more solid crystals 
(as there is great reason to believe to have been the case in granite), the friction 
will be lessened, especially in the central or inferior parts of the mass, where the 
expanding movement, or intumescence, may be supposed nearly uniform in all 
directions, lint in the lateral and higher portions directly exposed to the resist- 
ance and pressure of the overlying rocks shouldered off on either side by the ex- 
panding granitic axis, the movement will ])robably have been so predominant and 
extreme in a direction at right angles, or nearly so, to the pressure, as to give 
rise to a lamellar arrangement of the solid crystals, in the manner before indicated. 
In this manner he supposes the foliation or lamination of gneiss and mica-schist to 
have been produced through the "squeeze and jam" of the lateral and superficial 
portions of a granite mass expanding by increase of temperature, and the giving 
way of the overlying rocks, those portions being forced to move in the direction 
of the lamination while subject to intense pressure at right angles, or nearly so, 
to that direction. The autlior argues that it is not inconsistent with this view, 
to supjiose that a certain amount of re-crystallisation may have accompanied or 
followed this lamellar arrangement, in which case also the major axes of the 
crystals would be likely to take a direction perpendicular to the pressure, since 
the mobility necessary to the crystallific action will have been freer in that than 
in any otlier direction. He likewise points out that the influence of internal 
friction aecomi)anying motion under extreme and irregular jiressiires, must have 
been equally ojierative in the case of aqueous as of igneous rocks, under similar 
circumstances of imperfect liquidity, and irrespective of changes of temperature. 
And he suggests that to this cause may be attributable the internal structure of 
some veined marbles, calcareous breccias, serpentines, &c. ; as well as the cleavage 
of the slaty rocks; a.s, indeed, the experiments of Mr. Sorby and of Professor 
Tyndall have already indicated. He concludes by suggesting to all geologists 
engaged in the examination of rocks the above mechanical considerations, as 
likely to lead to more definite views than at present prevail as to the origin of 
the metamorphic schists, and the internal structure of many of tlie older and more 
disturbed rocks of all characters. 
"Wahwicksitiri: N.vtueal History and ARcn-T:oLOGicAL Society A^'D Field 
Club. — The council of this Society, in their twenty-second annual rciiort, read at 
the anniversary meeting on the 9th April last, annoiuicc numerous and valuable 
additions to their museum and library ; but they appear, as we gatlier from the 
report, to be deficient in local objects and books, &c., relating to their county. 
This is the great defect of most local museums, and that which causes too many of 
them to be justly regarded as mere ciu'iosity -shops. The council, however, appear 
